Concentration of partially polymerized diallyl phthalate



1952 J. ANDERSON EI'AL 2,613,201

CONCENTRATION OF PARTIALLY POLYMERIZED DIALLYL PHTHALATE Filed April 21, 1947 lnvznrors: John Andrzaon John W. Mzcorneg George E. Ham

Patented Oct. 7, 1952 CONCENTRATION OF PARTIALLY POLY- MERIZED DIALLYL PHTHALATE John Anderson, Berkeley, and John W. Mecorney, Albany, Calif., and George E. Ham, Dayton, Ohio, assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application April 21, 1947, Serial No. 742,820

8 Claims. 1

The present invention relates to the concentration of partial polymers of esters such as diallyl phthalate. More particularly, the invention relates to a process for concentrating esters by solvent extraction.

Esters such as diallyl phthalate are useful in the production of thermosetting resins and their utility is enhanced if they are polymerized in two stages. If one polymerlzes in two stages, shrinkage of the finished article is minimized and a shorter cure time is needed which reduces the cost of fabrication. It is also advantageous to partially polymerize the ester and to then-separate the soluble polymer from the monomer and utilize only the soluble polymer. found that partial polymers from low conversion processes, 1. e. where the initial polymerization is only permitted to-cause a slight degree of polymerization, are superior to polymers'produced by high conversion processes. On the other hand, the polymers s produced of the highest molecu- It has been- The objects of the present invention are accomplished by employing a dual solvent comcontaining solvent with most of the polymer and a small amount of the monomer.

It has been found that by properly selecting the concentrations of solvents and operating temperatures that substantially all. of the polymer recovered from the rafllnate layer'is of high molecular weight lar weight are superior to those of low molecular weight. 'It has also been found that for finished articles of thehighest quality, the initial polymerization should not be conducted in the presence of a solvent, or, if a solvent is used, the quantity of the solvent should be kept at a minimum. Articles produced from esters polymerized in the absence of solvents have greater scratch resistance andgreater hot hardness, i.e. they hold their shape better when first taken from the mold.

and that the ester having a low degree of polymerization will be found in the extract phase with the monomer. Thus, the present invention is advantageous over the heretofore known methods of precipitation polymers by adding water to acetone solutions of the polymers, because such precipitation methods result in the recovery of all of the polymer and not in the selective recovcry of only the most desirable portion of the polymer.

It is therefore an object of the present invention to provide a convenient and economical process for the separation of diallyl phthalate (and similar esters) monomer from olymers.-

It is a further object of this invention to provide a process whereby polymers of varying concentration may be produced so that one may obtain special solutions of polymers which are particularly adapted to certain uses. It is a further object of this invention to provide solutionsv of polymers which are stable and pumpable so that they may be readily stored and shipped and which involve no handling of solids or viscous 65% mass. by Weight of acetone in the solvent materials. Another object of this invention ispolymer to an insoluble and The process of the present invention may be does not desire a very high concentration of poly- .mer, for instance for the manufacture of contact laminates, a single stage will suflicebut if one desires a high concentration of polymer, as for use in laminating varnish or moldingpowder, it is preferred to utilize two or more stages.

It has been found preferable touse from about mixture used for the first stage of extraction. If over. 85% of acetone is used in the first stage, a complete solution of the partial polymer is obtained, so that there is no separation into phases.

However, if more than one stage of extraction is used,, the acetone concentration may be, as high as 87.5% in the second stage. If less than acetone is used, impractically high solvent to polymer ratios would be needed to obtain satisfactory high polymer separations. At a given solvent to partial polymer ratio, a greaterconcentration effect is brought about by the solu' tions having the higher acetone concentrations while, however, the polymer recoveries are in the reverse order being higher for the solvent mixtures having the lower acetone concentrations. By thesame taken, the selectivity between polymers' of different molecular weight is greater for those mixtures containing higher 31081701180011".-

centrations. i. e. solutions containing a large amount of acetone tend to give rafiinate layers containing only the higher molecular weight polymers and polymers of lower molecular weight go to the extract phase.

The amount of water in the acetone-water mixture has an effect on the viscosity of the extract which is produced. Those mixtures which contain a larger amount of aceto'ne'give raflinates which are more fluid, for a given polymer concentration, than those with a lesser amount of acetone. Therefore, it is preferredto operate in the final stage of extraction (or in the single stage if only one stage is used) with an acetone concentration near the upper limit. In general, it is preferred to operate the final stage with an acetone concentration of from about 80% to 87.5%.

'.I e volume of dual solvent which is used will depend upon the ultimate concentration of polymer which is desired and also the percentage of acetone which is used in making up the dual solvent. Satisfactory results will be obtained if from about 2.5 to 12 volumes of dual solvent are used per volume of partial polymer and it is preferred to use from about 3.5 volumes to 6 volumes.

The temperatureof extraction may vary from C. to 40 C. and. is not critical within this range. Generally satisfactory results are obtained at an intermediate point in this range, so that it is preferred to operate at temperatures of from about20 C. to about 30 C.

In performing the process of the present invention, the partial polymer may be produced and then the solvents added thereto, or less preferably} a portion of the solvents maybe added to the/monomer prior to polymerization. It is also possible to conduct two'or more extractions using different percentages of dual solvent in each stage and one may also vary the percentage of acetone in each stage. For instance, when makin a polymer solution in which-95% of the diallyl phthalate is in the form of polymer, one may conduct the first stage of extraction with about 620 volumes of a solvent containing-70% acetone and 30% water and conduct the second stage of extraction with about 2 volumes per volume of first-stagerafiinate of a solvent containing 85% acetone and 1 5% water.

The partial'polymerization of the ester is con ducted under mild polymerizing conditions so that little, if any, cross linkage between polymer molecules occurs and the production of an irifusible, insoluble polymer is avoided. For polymerization, the ester is preferably used without dilution although a small amount of a suitable solvent such as acetone may be used. A suitable catalyst such as air, benzoyl peroxide or tertiary-butyl hydroperoxide is then added and the mixture is heated to a temperature of from about 135 C. to 240? C. When the diallyl phthalate or other ester is from 20% to 40% polymerized it may be extracted in the manner described below. By the term 20% to 40%" polymerized is meant the condition when from 20% to 40% ofthe ester molecules exist in the polymerized form, the balancebe'ing still in the form of monomer. The extract from the separation contains alarge percentage of monomer and'may' be returned to the polymerization vessel. The solvent may-be removed or reduced in quantity before the extract. is Iv recycled to the polymerization stage. a

In the drawing there is illustrated in diagrammatic manner a preferred method of applying the present invention. In this particular embodiment, there is shown a polymerization step followed by two stages of solvent concentration. In the drawing there is illustrated a polymerization vessel I, provided with an inlet 2 for the introduction of diallyl phthalate and an inlet 3 for the introduction of air or other polymerization catalyst, such as a peroxide. If desired, another inlet 4 may be provided for the introduction of water or other vaporizable liquid. The

use of water is optional and during polymerization the water is evaporated, tending to remove at least a part of the heat of polymerization. The vessel I is provided with suitable heating and stirring means, as illustrated, so that the vessel may be heated to the desired temperature to initiate the polymerization reaction. The heating means may consist of a steam coil 1 within the vessel. Recycle diallyl phthalate may be introduced into line 2 through line 5 while fresh diallyl phthalate is introduced through line fi. The partial polymer produced in polymerization vessel 1 is withdrawn from vessel I through line 8, mixed wtih a mixture of acetone and water. and recycle partial polymer from line I0 and introduced-into the first stage mixer 9. These components are supplied to line In by line II where fresh acetone-water mixture is introduced, line [2 which lead from the steam stripper l4 and recycle second stage extract containing par-- tial polymer is supplied by line [3 which leads from the upper phase produced in the second stage settler 23. 'Mixer 9 insures rapid and thorough mixing of the partial polymer with the acetone-water mixture. The residence time in mixer 9 is only suflicient-to insure thorough mix ing of the ester-and solvent and may be on the order of one-half minute. From mixer 9, the

ester-solvent mixture is conveyed to settler It by means of line'l 5. Settler I6 is sufficiently large to permit stratification to take place which ordinarily requires a residence time of from 2 to 3 hours. I settler l6, two phases are formed, an extract or'upper phase; containing acetone, Water, a minor portion of the polymer and a major portion of the monomer. 'The extract phase is with drawn byline I! and is introduced into steam stripper M, the function of which willbe described later. Therafflnate phase is withdrawn through line I8 andis -mixed with additional acetone-water mixture from line [9. Line [9 receives recycle acetone-water from line l2 and fresh acetone-Water mixture-fromline. 20. The 1 mixture thus producedis introduced into mixer 21, which is similar to mixer 9, and is then introduced by line 22 into the second stage settler 23, which is similar to settler IS. The residence time in'settler 23 will be on the order of 10-12 hours. Two phases are formed,and the raffina-te is taken off as finished product by line 24. A

typical-composition of the finished product is:-

polymer 63.2%, monomer.2.3.%, acetone 31.8%

and water 2.7% (all parts'by weight). This'productv may be easily stored, andutilized as hereinafter described. 'The. extract from settler 23 contains acetone, water, a small amount of polymer and a large amount of monomer and may be withdrawn by line [3 and recycled as illustrated. The extract which is fed into the steam stripper 14 from the first stage settler leis consisting of acetone and water which is taken overhead and condensed by condenser 26. A portion of this mixture may be returned to the column line 21 as reflux and the balance is recycled by line 12 as solvent to the first and second stages of extraction. The bottoms from the steam stripper consist almost entirely of water, monomer and low molecular weight polymer. This mixture is withdrawn from the bottom of the column, and a portion may be passed through a reboiler 28 and returned to the column. The balance is introduced into separator 29 by line 30 where two phases are formed. The upper phase consists almost entirely of water and. may be removed by line 3i and the phase consists almost entirely oi monomer and low molecular weight polymer and may be recycled to the polymerization vessel by means of line 5.

It is apparent that many modifications may be made in the apparatus described above. For instance, a single stage may be employed instead of the double stage of extraction illustrated. If this is done, the rafiinate from the single stage becomes the product and the extract is passed to cheat the final polymerization or cure. such as alpha cellulose may be added to the solution to make a plastic dough. The mixture can be milled until the solvent evaporates and the resulting dough is suitable for compression or extrusion molding.

The following non-limiting examples illustrate the operation of the invention:

Example I A partial polymer of diallyl phthalate containing 30.5% polymer by weight was extracted with a solvent consisting of a mixture of acetone and water. A 2 stage countercurrent extractor was employed substantially like that illustrated in the drawing except the entire solvent feed was through line 20, no make-up solvent being addedthrough lines II or l2. The temperature of operation was varied as well as the ratio of the solvent to partial polymer and the ratio of Fillers through a steam stripper to form an overhead basis i. e. the balance is monomer. The followmixture of acetone and water which may be ing results were obtained:

Analysis of rafllnate flolvegtlto Pertcent E i 'Peroent par 2 ace one st mated diallyl Expgment g polymer in solvent viscosity in phthalate (ratio by (balance Percent Percent polses recovered weight) water) polymer solvent as polymer 20-25 2. 5 1 80 98 32. 4 52 12 58. 5 20-25 8. 0 1 80 98 33. a 11 01. 0 20-25 4. 5 1 80 98 31. o 1c 08. 2 20-25 0.0 1 98 28.9 140 37 02.5 20-25 3. 0 1 75 08 31. 4 04 14 70. 8 20-25 4. 0 1 75 98 20. 4 28 77. 2 20-25 0. 0 1 75 98 23. 4 70. 2 20-25 3. 0 75 98 28. 8 24 77. 4 20-25 4. 5 1 75 98 29. 3 20 77. 1 20-25 8. 0 1 75 98 29. 6 120 25 70. o 40 3. 0 1 75 98 20. 8 90 21 70. 5 40 4. 5 1 75 98 27. 0 80 72. 7 20-25 4. 5 1 70 94. 6 20. 2 150 32 85. 2 20-25 0. 0 1 70 08 26. 0 40 81. a

recycled for reuse as a solvent and the bottoms Example II from the stripper may be returned to the polymerization vessel for further polymerization.

The polymer solution produced according to the present invention may be stored, shipped, pumped and otherwise handled without difiiculty. The polymerization catalyst may be added to the solution just before it is used. The solution is suitable for dipping cloth or paper for uses "such .as the preparation of laminates.

A two stage countercurrent extractor was used substantially like that illustrated in the draw- 50 mg for the extraction of a partial polymer of diallyl phthalate containing 30.5% polymer. Test solvent was added through line 20 as well as through lines ll and/or I2. The conditions of operation were varied as in Example I and 55 the final rafflnate was analyzed to determine its solvent content and also to determine the per- Paper which has been dipped in the solution centage of polymer on a solvent-free basis. The may be dried to remove the solvents and may following results were obtained:

First Stage Second Stage S 01V em 1 Solvent Analysis of Final Rafllnate if??? 1 E eriment Tem 18 y i No. *0? Solvent Percent Solvent Percent viiscossity phthalat;

to acetone to acetone Percent Percent p0 Se recoYem polymer polymer in polymer solvent as Do ymer ratio solvent ratio solvent at C at 42 C.

1 This composition is that of make-up solvent. Because this was mixed with second stage extract, the actual solvent used ior extraction had a higher percentage of acetone and was of a higher solvent to polymer ratio than indicated.

then be rolled or calendered. The final user of the paper need only apply heat and pressure We claim as our invention:

tremor. diallyl phthaiateztpartiallpolymersscomw prislng polymerizingiidiallyl-iphthalatezwin axpolye merization zone: until polymerization; is" from 20%; to. 40%: complete; contacting theipartial polymerrsotproduced with from 2.5 to lzwvolumes prising-1; dual; solvent and" abottoms; is produced containinggwatersanddiallyl phthalate monomer, separating the 'water from themonomcrand returningithe monomer: to the polymerization vessel, ,contactinggthe lower phase-withirom' 2.5-- to 12.-volumes per. volume of partial polymer of. an, acetone-water dual solventcontain-ingfrom 80%,to87 /g1% acetone to again-form two: phases,

separating, the, phases, recovering thebottom-'- phase-as product and 'ecyoling the upper phase to the e iiluent oi; the polymerization zone,-v the:

above extractions being conducted ata temperature ofirom C. to 40? C.

2.]The process of claim 1 whereinfrom-t-tov 5 volumes of the dual solvent areusedin'each extraction per volume of partial polymer.

3. A continuous process for producing a concentrated solution of"di'allyl phthalate polymer comprising polymerizing diallyl phthalatein-aa vesseluntil polymerization is to %;fcomplate; contacting 'the partial polymer: so produced;

part of thediallyl phthalate monomer and lower phase containing; dual solvent and'a major part:

of-the diallyl phthalate, polymer, separating the".

phases, returning .'-the upper phase to the polymerization zone, contacting-theslower phase with 255:volumes to 12 volumes per volume ofpartial polymer of a dual. solvent consisting of, 80% to- 875% acetone, and balance'water, so as to form two more phases, separating the phases, returning the upper phaseto'thepolymerization zone, and recoveringrthe lower phase. asv the? desired diallylc-phtha-late polymer: concentrates.

4. A=prooess for; concentrating.diallylphthalate:

polymer comprising contacting a I partial polymer ofv diallyl phthalate: consisting of: a mixture of 1 diallyl phthalate monomer and polymerobtained by exposing monomeric diallyl phthalateto polymerizing conditionsuntil 20 i to 40 of monomen has been converted '-t0- soluble, fusible -'poly'- mer,- with 2.5 13012 volumes per-volume of partial polymer of a dual "solvent consistingof 65% to 85% acetone, the balance being water, whereby two phases are formed, an upperphase containing part of said dual solvent and a major part of theqdiallyl phthalate monomer and a lower phase containing dual solvent and a major part of the diallyl phthalate polymer, separating the two phases,- contacting the lower phase with 2.5 volumesto 12 volumes per volume of partial polymer of-a dual -solventconsisting of 80% to- 87.5% acetone, an'd'balance water,so as to form 7 two. more=phases, separating the phases and recovering the lower phase as thedesired diallyl phthalate polymer concentrate.

. 5.- Arcontinuousprocess for producing v azcone centrated solution of diallyl phthalate polymers comprising polymerizing;.;dia1:1 y1 phthalate-in a vessel: until;:it. is-;2 0% ates-40%@polymerized; ,con-

tacting; trier partial: pol'imer; 50: produced with 2.5:; volumes to 12.:volizmes per volume; of partial? polymer; of: a dualzsolvent consisting: 301: 65 %E: to; 85% f by-- weight' of: acetone; the: balance being; water; whereby two phases arei'formed, an upper." phase acontaining .part ofzsaicl'dual solvent and: a;. major: part. of: the diallyl phthalate .monomer" and 1 lower. phaseicontaining-rdual. solvent and-a r maj ortp artiof'; the: diallyl. phthalate: polymer; sop-- arating; the": two": phases, 3 returning; the;-: upper:-

ph'asezto; the: polymerization vessel, .andrrecovera iIIE-IthETlOWEI phase=as the-.desi-redz diallyl phthaleateepolymer' concentratezx i 61 A-' processforrconoentrating :diallylt phthal-f atei-x polymers" comprising contacting; an. partial" polymer rof- .diallyl phthalate consistingcofirazmimture of diallyl phthalate "monomer; and" polymer.- obtained by exposing monomeriodiallyl phthal-r atea to polymerizing; oonditionsauntil ,20 =to..40

of monomer has been converted to: solublerillSlblepolymer, with 3;5-to.-6--volumes per volumeof partial. polymer ofia .dual solventconsisting; of. 65% to 85% by; weight'opacetone, the-.balancer being water; whereby TbWO' phases are formed an upper; phase: containing. part of said dual- S01?- vent, and a'majorpart of'the'diallyl phthalate-.- monomer. and. a lower phase containing dual solvent and a major part of the diallyl phthalate polymer, separating the two phases and recovering the lower phase as the desired diallyl phthalatezpolym'er concentrate, the process being conducted at a temperature between 0 C. and 40 C.

'1. A process for concentrating diallyl phthalate p o1mers comprising contacting a partial polymer of 'diallylphthalate consisting of a mixture'of diallyl phthalate monomer and polymer obtained by exposing monomeric diallyl phthalate to polymerizingconditions until 20% to 40% of monomer has been converted to soluble, fusible polymer, with- 2.5, volumes to 12 volumes per volume of partial polymer of a dual solvent consisting, of 65% to 85% by weight of acetone, the balance being water, whereby two phases are formed, an upper phase containing part of said dual solvent and a. major partof the diallyl. phthalate monomer. and-a lower phase-contaim ing dual solventhamajor part of-. the diallyll phthalate, polymer, separating the two. phases and recoveringtherlower phase. as;the desired:

diallyl. phthalate polymer. concentrate;

8. A process for concentrating .diallyl patterate polymers comprising, contacting a... partialfl polymer, of diallyl phthalate consisting of vla .mix=- solvent consisting of 65% to 85% by weight of acetone, the balance being water, whereby two phasesv are. formed, separating the two phases, contacting the lower phase with about 2.5 volumesper volume of partial'polymer of a dual solvent consisting of to 37.5% acetone, the balance being water, so as to again form two phases; separating the two phases and recovering. the bottom phase as thedesired diallyl phthalater-polymer'concentrate, the above extractions being conducted at a temperature between 0 C. and 40. C.

JOI-INANDERSON.

JQHNFW. MECORNEY.

GEORGEE. HAM.

(Referencesqonfollowinn'pagfl 9 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,024,666 Stand et a1 Dec. 17, 1935 2,273,891 Pollack et a1. Feb. 24, 1942 10 QTHER REFERENCES Cragg et aL: Chemical Reviews (August 1946), pp. '79, 82, 83, 89, 90, 99-102, 104-105, and 110-118. Rogovin et a1.: Kolloid-Z, 76, 210-13 (1936).

Craik et aL: Trans. Faraday Soc. 27, 756-67 I 

1. A PROCESS FOR PRODUCING A CONCENTRATED SOLUTION OF DIALLYL PHTHALATE PARTIAL POLYMERS COMPRISING POLYMERIZING DIALLYL PHTHALATE IN A POLYMERIZATION ZONE UNTIL POLYMERIZATION IS FROM 20% TO 40% COMPLETE, CONTACTING THE PARTIAL POLYMER SO PRODUCED WITH FROM 2.5 TO 12 VOLUMES PER VOLUME OF PARTIAL POLYMER OF A DUAL SOLVENT, SAID DUAL SOLVENT CONTAINING FROM 65% TO 85% ACETONE AND THE BALEANCE WATER, WHEREBY TWO PHASES ARE FROMED, SEPARATING THE PHASES AND SUBJECTING THE UPPER PHASE TO STEAM STRIPPING WHEREBY AN OVERHEAD FRACTION IS PRODUCED COMPRISING DUAL SOLVENT AND A BOTTOMS IS PRODUCED CONTAINING WATER AND DIALLYL PHTHALATE MONOMER, SEPARATING THE WATER FROM THE MONOMER AND RETURNING THE MONOMER TO THE POLYMERIZATION VESSEL, CONTACTING THE LOWER PHASE FROM 2.5 TO 12 VOLUMES PER VOLUME OF PARTIAL POLYMER OF AN ACETONE-WATER DUAL SOLVENT CONTAINIG FROM 80% TO 87 1/2% ACETONE TO AGAIN FORM TWO PHASES, 